Lake Sturgeon - Life Cycle

Lake sturgeon migrate to their annual spawning grounds between late
April and early June, preferring to spawn in shallow, rocky areas
along river banks. Sturgeon spawning is dependent on water
temperature and flow. During seasons when water flow is high and
water temperatures rise slowly spawning begins when water
temperature reaches 53 degrees F. In contrast, during seasons of
low water flow and more rapid water temperature rise, spawning does
not begin until water temperatures reach 58-59 degrees F.

Males arrive at the spawning sites ahead of the females, cruising
in groups of eight or more, often so close to the surface that
their tails, backs, or snouts are out of the water. Spawning begins
as soon as a ripe (sexually ready) female enters the group. The
males swim alongside the female, usually against the current,
vigorously thrashing their tails as they release milt (sperm) while
the female drops her eggs. The fertilized eggs, each about
one-eighth inch in diameter, are sticky and cling to rocks and
other solid materials in the water until they hatch. There is
considerable variation in the number of eggs produced by the
females of the same weight - the quantity can range from 50,000 to
700,000 eggs in one season.

The eggs hatch in five to eight days, depending on the water
temperature. In 12 to 14 days, the fry (newly hatched fish) are one
inch long and have fully developed mouths and barbels.

Spawning frequency - A female sturgeon reaches sexual maturity when
she is 24 to 26 years old and about 55 inches long, and will spawn
once every four, five, or six years thereafter. Males mature at
about 15 years, when they are about 45 inches long. Most males
spawn every other year, while some do so every year.

Lake sturgeon grow larger and live longer than any other fish in
Wisconsin. Females live longer than males; 97% of all sturgeon over
30 years old are females. An 82-year-old caught in Lake Winnebago
in 1953 is on record as the oldest lake sturgeon in Wisconsin - a
mere whippersnapper when compared to the 152-year-old, 215-pound,
81-inch long old-timer hauled up from the bottom of Lake of the
Woods in Ontario, Canada that same year.

At first, lake sturgeon grow more rapidly in length than in weight,
but this trend is reversed as the fish ages. Growth depends on
several factors, including water temperature and available food.